# Phase 4: Threshold and Spline Estimates


## ca_gdp

| Model | Z₁ (base) | Key Interaction | N | R² |
|---|---|---|---|---|
| Baseline | 29.765** | -- | 7624 | 0.025 |
| OADR>15% | 21.884 | -0.952 | 7624 | 0.032 |
| OADR>20% | 22.008 | 0.494 | 7624 | 0.030 |
| OADR>25% | 24.032* | 10.180 | 7624 | 0.028 |
| Income saturated | 31.374 | low:-75.2, high:64.9 | 7624 | 0.052 |
| Combined | 7.266 | see table | 7624 | 0.057 |

## gross_savings_gdp

| Model | Z₁ (base) | Key Interaction | N | R² |
|---|---|---|---|---|
| Baseline | 114.147*** | -- | 6642 | 0.130 |
| OADR>15% | 125.995*** | -6.360 | 6642 | 0.127 |
| OADR>20% | 121.750*** | -8.241 | 6642 | 0.128 |
| OADR>25% | 119.723*** | -10.610 | 6642 | 0.128 |
| Income saturated | 95.470*** | low:60.1, high:-0.4 | 6642 | 0.224 |
| Combined | 133.517*** | see table | 6642 | 0.185 |

## gross_investment_gdp

| Model | Z₁ (base) | Key Interaction | N | R² |
|---|---|---|---|---|
| Baseline | 32.616*** | -- | 6620 | 0.068 |
| OADR>15% | 35.835*** | -2.071 | 6620 | 0.068 |
| OADR>20% | 34.887*** | -3.782 | 6620 | 0.069 |
| OADR>25% | 33.651*** | -15.568 | 6620 | 0.071 |
| Income saturated | -1.038 | low:74.6, high:21.3 | 6620 | 0.086 |
| Combined | 40.972*** | see table | 6620 | 0.074 |

## nfa_gdp

| Model | Z₁ (base) | Key Interaction | N | R² |
|---|---|---|---|---|
| Baseline | -0.966 | -- | 7712 | 0.076 |
| OADR>15% | -2.189 | 0.293 | 7712 | 0.086 |
| OADR>20% | -1.994 | 0.447 | 7712 | 0.085 |
| OADR>25% | -1.762 | 0.593 | 7712 | 0.083 |
| Income saturated | 1.520 | low:-0.9, high:-4.4 | 7712 | 0.102 |
| Combined | 0.575 | see table | 7712 | 0.128 |

*OADR splines: Z₁×I(OADR>threshold). Positive = stronger effect above threshold.*
*PanelGLS with AR(1). \*p<0.1, \*\*p<0.05, \*\*\*p<0.01*
